<!-- 配置Filter要攔截的目標(biāo)資源 -->
<filter-mapping>
    <!-- 指定這個mapping對應(yīng)的Filter名稱 -->
    <filter-name>FilterDemo01</filter-name>

    <!-- 通過請求地址模式來設(shè)置要攔截的資源 -->
    <url-pattern>/servletDemo01</url-pattern>
</filter-mapping>

<filter-mapping>
    <filter-name>Target02Filter</filter-name>

    <!-- 模糊匹配：前杠后星 -->
    <!--
        /user/demo01
        /user/demo02
        /user/demo03
		/demo04
    -->
    <url-pattern>/user/*</url-pattern>
</filter-mapping>

<filter>
    <filter-name>Target04Filter</filter-name>
    <filter-class>com.carson.filter.Target04Filter</filter-class>
</filter>
<filter-mapping>
    <filter-name>Target04Filter</filter-name>
    <url-pattern>*.png</url-pattern>
</filter-mapping>

<filter-mapping>
    <filter-name>Target05Filter</filter-name>
    <!-- 根據(jù)Servlet名稱匹配 -->
    <servlet-name>Target01Servlet</servlet-name>
</filter-mapping>

public class ServletDemo01 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("ServletDemo01接收到了請求...");
    }
}

<servlet>
    <servlet-name>servletDemo01</servlet-name>
    <servlet-class>com.carson.ServletDemo01</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>servletDemo01</servlet-name>
    <url-pattern>/ServletDemo01</url-pattern>
</servlet-mapping>

<!--創(chuàng)建多個Filter攔截Servlet：-->
<filter-mapping>
    <filter-name>TargetChain03Filter</filter-name>
    <url-pattern>/ServletDemo01</url-pattern>
</filter-mapping>
<filter-mapping>
    <filter-name>TargetChain02Filter</filter-name>
    <url-pattern>/ServletDemo01</url-pattern>
</filter-mapping>
<filter-mapping>
    <filter-name>TargetChain01Filter</filter-name>
    <url-pattern>/ServletDemo01</url-pattern>
</filter-mapping>

<dependencies>
        <!--JSP依賴-->
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.3</version>
        </dependency>
        <!--Servlet依賴-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
        </dependency>
        <!--JSTL表達(dá)式的依賴-->
        <dependency>
            <groupId>javax.servlet.jsp.jstl</groupId>
            <artifactId>jstl-api</artifactId>
            <version>1.2</version>
        </dependency>
        <!--standard標(biāo)簽庫-->
        <dependency>
            <groupId>taglibs</groupId>
            <artifactId>standard</artifactId>
            <version>1.1.2</version>
        </dependency>
        <!--鏈接數(shù)據(jù)庫-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.19</version>
        </dependency>
    </dependencies>

package com.carson.filter;

import javax.servlet.*;
import java.io.IOException;

public class CharacterEncodingFilter implements Filter {
    //初始化:當(dāng)web服務(wù)器啟動時,就自動初始化了,隨時等待過濾對象的出現(xiàn)
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("CharacterEncodingFilter已經(jīng)初始化");

    }

    /*
    1:過濾器中的所有代碼,在過濾特定請求的時候都會執(zhí)行
    2:必須寫chain.foFilter()方法讓過濾器繼續(xù)前進(jìn)
    */

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
		//轉(zhuǎn)換request和response為HttpServlet類型
		HttpServletRequest request = (HttpServletRequest) request;
		HttpServletResponse response = (HttpServletResponse) response;
		解決請求參數(shù)的中文亂碼問題
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=UTF-8");

        System.out.println("CharacterEncodingFilter執(zhí)行前");
        //讓我們的請求繼續(xù)走,如果不寫,程序到這里就會被攔截停止
        //即這句代碼表示放行
        filterChain.doFilter(servletRequest,servletResponse);
        System.out.println("CharacterEncodingFilter執(zhí)行后");

    }
    //銷毀:當(dāng)web服務(wù)器關(guān)閉的時候,會進(jìn)行銷毀
    public void destroy() {
        System.out.println("CharacterEncodingFilter已經(jīng)銷毀");

    }
}

<!--注冊filter過濾器,類似注冊servlet-->
    <filter>
        <filter-name>CharacterEncodingFilter</filter-name>
        <filter-class>com.carson.filter.CharacterEncodingFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>CharacterEncodingFilter</filter-name>
        <!--filter的路徑配置:只要是/servlet的任何請求,都會經(jīng)過這個過濾器-->
        <!--即設(shè)置過濾器的過濾請求路徑-->
        <url-pattern>/servlet/*</url-pattern>
    </filter-mapping>